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/**
* CloudGraph Community Edition (CE) License
*
* This is a community release of CloudGraph, a dual-license suite of
* Service Data Object (SDO) 2.1 services designed for relational and
* big-table style "cloud" databases, such as HBase and others.
* This particular copy of the software is released under the
* version 2 of the GNU General Public License. CloudGraph was developed by
* TerraMeta Software, Inc.
*
* Copyright (c) 2013, TerraMeta Software, Inc. All rights reserved.
*
* General License information can be found below.
*
* This distribution may include materials developed by third
* parties. For license and attribution notices for these
* materials, please refer to the documentation that accompanies
* this distribution (see the "Licenses for Third-Party Components"
* appendix) or view the online documentation at
*
* The adapted shunting-yard algorithm in general uses a stack of
* operators and operands, and as new binary tree nodes are detected and
* created they are pushed onto the operand stack based on operator precedence.
* The resulting binary expression tree reflects the syntax of the
* underlying query expression including the precedence of its operators.
*
*
* The use of binary expression tree evaluation for post processing
* of graph edge results is necessary in columnar data stores, as an
* entity with multiple properties is necessarily persisted across multiple
* columns. And while these data stores provide many useful column oriented
* filters, the capability to select an entity based on complex criteria
* which spans several columns is generally not supported, as such filters are
* column oriented. Yet even for simple queries (e.g. "where entity.c1 = 'foo'
* and entity.c2 = 'bar'") column c1 and its value exists in one cell and
* column c2 exists in another table cell. Since columnar data store
* filters cannot generally span columns, both cells must be returned
* and the results post processed within the context of the binary
* expression tree.
*
*
* @author Scott Cinnamond
* @since 0.5.2
*
* @see EdgeRecognizerRelationalBinaryExpr
* @see EdgeRecognizerWildcardBinaryExpr
* @see ExprAssembler
*/
public class EdgeRecognizerSyntaxTreeAssembler extends PathPredicateBinaryExprTreeAssembler
{
protected DataGraphConfig graphConfig;
/**
* Constructs an assembler based on the given predicate
* and graph edge type.
* @param predicate the predicate
* @param edgeType the graph edge type which is the type for the
* reference property within the graph which represents an edge
* @param rootType the graph root type
* @param graphConfig the graph config
*/
public EdgeRecognizerSyntaxTreeAssembler(Where predicate,
DataGraphConfig graphConfig,
PlasmaType edgeType, PlasmaType rootType) {
super(predicate, edgeType, rootType);
this.graphConfig = graphConfig;
}
@Override
public RelationalBinaryExpr createRelationalBinaryExpr(Property property,
Literal literal, RelationalOperator operator) {
String qual = Bytes.toString(this.contextQueryProperty.getPhysicalNameBytes());
String delim = this.graphConfig.getColumnKeySectionDelimiter();
String qualPrefix = qual + delim;
return new EdgeRecognizerRelationalBinaryExpr(
property, qualPrefix, literal, operator);
}
@Override
public WildcardBinaryExpr createWildcardBinaryExpr(Property property,
Literal literal, WildcardOperator operator) {
String qual = Bytes.toString(this.contextQueryProperty.getPhysicalNameBytes());
String delim = this.graphConfig.getColumnKeySectionDelimiter();
String qualPrefix = qual + delim;
return new EdgeRecognizerWildcardBinaryExpr(
property, qualPrefix, literal, operator);
}
@Override
public LogicalBinaryExpr createLogicalBinaryExpr(Expr left, Expr right,
LogicalOperator operator) {
return new DefaultLogicalBinaryExpr(left,
right, operator);
}
}